Stone Age Online is the code name for a work in progress 3D multiplayer game that I’m developing. It’s written in Java and (after a brief spell of using C++ with Ogre3D for the client) currently uses a custom rendering engine, although I am intending on porting it to jMonkeyEngine.
Both the client and server are written in Java. Currently the client uses a custom rendering engine on top of LWJGL, although I am planning to port it to jMonekyEngine for more efficient use of development time (too much effort has gone into the engine rather than the game itself).
Not much of this has really been planned out yet - currently, all the focus is on the technical side of things. My intention is that it’ll be a sandbox game, taking several ideas from games like Wurm Online.